Statistics showing the number of teachers that leave state funded schools in England in each year are publicly available from Table 7b of the additional tables at the following link:
Table 7b of the additional tables shows that between 2014 and 2015, 43,070 qualified teachers left the profession (full-time equivalents, FTE). This is equivalent to 10.0% of teachers. The total number of FTE teachers leaving in any one year includes those who are retiring, those moving to other education sectors e.g. Independent schools or FE and those leaving the profession, some of whom later return.
During the same period (2014 to 2015), 45,810 FTE teachers entered service in a state funded school. This is equivalent to 10.5% of teachers. The rate of entry of teachers has been higher than the rate of those leaving throughout the period of 2011 to 2015. In 2015, 14,060 FTE teachers returned to the profession.
These statistics are sourced from the annual School Workforce Census.