This is from the IPA Juniority page. Not sure of the parameters but believe these numbers are based on age 60, not 65. If so, then the early numbers are skewed high, and the 2013 numbers are skewed low. Am posting only for an idea of year to year numbers. Called IPA to get current demographics and will post when received.

Near Term Retirements
Year # Retirements Chart
2009 60
2010 44
2011 51
2012 61
2013 65
2014 79
2015 100
2016 96
2017 97
2018 88
2019 138
2020 140
2021 177
2022 161
2023 188