The Babylonian captivity (605-536 B.C.) lasted seventy years because Israel violated 70 Sabbath years. (Leviticus 26:31-35; 2 Chronicles 36:21,22) God reckoned the apostacy of Judah and Israel to be 430 years. (Ezekiel 4:5,6) The number of Sabbath years in 430 years is 70! This proves mathematically a Jubilee cycle has to be a repetition of “seven sevens” which is 49 years. God established the annual feast of Pentecost as an annual “shadow” of the Jubilee Calendar. The 50th day always fell on the first day of the week. - Wake Up America
Some will notice and question how one can get 70 Sabbath years out of 430 years. It is true, you only have 7 Sabbath years in a 49 year period, but you also have a Jubilee year (the 1st year of the 49 year cycle), which is a rest year also. Hence, there are actually 8 years in every 49 where the Land of Israel is supposed to rest, thus one cannot simply divide 430 by 7.
In his book, Know the Future p.96, Tim McHyde goes into great detail explaining why the Jubilee (Yovel) is a 49 year cycle, not a 50 year cycle. An opposing and prevailing Talmudic view (also held by many End Time scholars) is that there is a 49th, 50th, and then a separate 1st year (starting the count anew). McHyde writes:
Identifying the historic Sabbath and Jubilee year cycles is not as hard as it at first sounds. As we covered above, every Sabbath year must be a multiple of seven years from any other, just as every Jubilee year must be a multiple of 49 years (not 50) from any other. So, if you have evidence for enough Sabbath or Jubilee years across history, you can easily validate them against each other and come to a harmony that points to what the true cycles are. p.98
Qadesh La Yahweh Press is one of the few groups of chronologists that go by the 49 year cycle (continuous cycle of 7 years). In other words, instead of adding 50 to 50 to 50 and so on... they add 49 to 49 to 49. What follows is one of their more important findings:
"...the book of Nehemiah places Ezra's public reading of the Law during the Feast of Tabernacles, thereby signifying a sabbath year, in the seventh month of the twentieth Persian year of Arta-xerxes I, while Josephus, I Esdras, and the book of Ezra place it in his eighth Babylonian year. Nevertheless, both dates represent the same year, 456/455 B.C.E. The next year, 455/454 B.C.E., was a Jubilee. As we proceed with the evidence for subsequent sabbath years, it will become quite apparent that these above dates are correct and represent the original sabbath and Jubilee cycle." -The Sabbath and Jubilee Cycle, p.168.
Connecting the start of Jesus/Yehoshua's ministry to a Sabbath Year, McHyde writes:
...if 456/455 BCE was a Sabbath year, then 28/29 CE, some 69 Sabbath year cycles later, would indeed be a Sabbath year (-456 + 7 * 69 + 1 for no year zero). If Jesus proclaimed a Sabbath year to fulfill Isaiah 61 at the end of the 69th Week, then we can reasonably expect him to fulfill that prophecy fully in another Sabbath year at the end of the 70th Week. p.99
2009/2010 CE will be the next Sabbatical Year (according to this reckoning), with 2016, 2023, 2030, 2037, 2044, etc... following subsequently. Also, 2045/2046 CE will be the next known Jubilee Year based upon the findings of Yahweh.org and others (49 * 39 + 134 = 2045). 134 CE was found to have been a Jubilee Year, including several confirmed previous Jubilee years that reinforce the 134 CE dated event.