Year Total membership
2008 1,665,924
2009 1,743,232
2010 1,790,393
2011 1,940,486
2012 1,956,201
2013 2,016,449
2014 2,103,547
2015 2,046,745
2016 2,087,018
2017 2,292,509
2018 2,312,170
2019 2,351,783