Latest update:

A - Feb. 2013, June 2014, Nov. 2014 (twice), Dec. 2015, Nov. 2016, May 2017, Sept. 2017, April 2018, April 2019

B - June 2012, July 2012, March 2013, Jan. 2014, Feb. 2014, Oct. 2015, March 2016, April 2017, Feb. 2018, Dec. 2018

C - July 2012, April 2014, July 2014, Sept. 2014, Aug. 2015, Feb. 2016, Jan. 2017, Jan. 2018, March 2018, May 2018, Jan. 2019

D - June 2012, June 2014, May 2015, Feb. 2016, March 2017, Feb. 2018, Dec. 2018, April 2019

E - May 2012, Feb. 2014, Sept. 2014, July 2015, Dec. 2015, April 2016, June 2017, Feb. 2018, Jan. 2019

F - Feb. 2014, April 2015, Nov. 2015, Aug. 2016, March 2017, June 2017, April 2018, Oct. 2018

G - Nov. 2013, Dec. 2013, Oct. 2014, Aug. 2015, Oct. 2016, Feb. 2017, Jan. 2018, Aug. 2018

H - July 2012 (twice), Sept. 2014, Dec. 2015, March 2016, July 2017, April 2018, Feb. 2019

I - June 2014, May 2015, Nov. 2016, Aug. 2017, May 2018

J - July 2012, July 2014, Feb. 2015, Oct. 2015, May 2016, Jan. 2017, Aug. 2017, March 2018, Jan. 2019

K - Nov. 2013, Jan. 2015, March 2016, Aug. 2016, Sept. 2017, July 2018

L - Nov. 2012, Nov. 2013, Aug. 2014, Sept. 2015, Jan. 2016, Jan. 2017, May 2017, Nov. 2017, Aug. 2018, March 2019

M - June 2012, July 2012, Oct. 2013, April 2014, May 2014, Oct. 2014, Jan. 2016, Feb. 2017, Sept. 2018, March 2019

N - Aug. 2012, Aug. 2014, Aug. 2015, June 2016, Aug. 2017, Sept. 2018

O - Feb. 2014, Dec. 2014, July 2015, Dec. 2016, Sept. 2017; Oct. 2018

P - Oct. 2013, Feb. 2014, June 2015, Feb. 2016, Oct. 2016, July 2017, Oct. 2018, March 2019

Q - Nov. 2014, March 2016, Oct. 2017, Nov. 2018

R - Oct. 2013, March 2014, Oct. 2014, Nov. 2015, Dec. 2015, Feb. 2017, July 2018, Feb. 2019

S - Oct. 2013, Dec. 2014, June 2015, March 2016, May 2016, March 2017, Nov. 2017, Jan. 2018, Dec. 2018, March 2019, April 2019

T - May 2014, Jan. 2015, March 2015, Sept. 2015, May 2016, Sept. 2016, Nov. 2017, Nov. 2018, Jan. 2019

U - April 2014, June 2016, Dec. 2017, Nov. 2018

V - Jan. 2015, May 2016, May 2017, Oct. 2018

W - May 2013, March 2014, May 2014, Aug. 2014, Oct. 2015, Aug. 2016, Jan. 2017, May 2018

X - April 2015, Dec. 2016, Jan. 2018

Y - April 2015, April 2017, Nov. 2018

Z - March 2014, Feb. 2017, Nov. 2018

Updated to post 7296.