More random stats....
Currently there are
5 players with 1000+ career runs and a 50+ average (Marnus + "big 4")
Another 5 averaging 45-50 (Warner, Rohit, Taylor, Pujara, Agarwal).
And 7 more averaging 40-45.
The 20th best average for players with 1000+ runs is Markram at 39.7
Go back 10 years to the end of 2011:
There were 12 players with 1000+ runs and averaging 50+. Jonathon Trott was top of the list, then Kallis, Sangakkara, Tendulkar, Dravid, Younis Khan, Samaraweera, Bravo, Ponting, Jayawardene, Pietersen, Hussey.
Another 9 were averaging 45-50 : Cook, Smith, de Villiers, Bell, Chanderpaul, Amla, Laxman, Misbah, Clarke
The 20th best average was Misbah's 46.35
Another 12 players were averaging over 40, and the top sub 40 average was Shane Watson in 34th.
At end of 2001
8 x 50+ (Tendulkar top with 57.96, then Flower, Richardson, Dravid, Martyn, Gilchrist, Waugh, Lara)
6 more 45-50 and a total of 29 players averaging 40+
20th best was Mohammad Yousuf on 42.98.
At end of 1991
6x 50+ averages (Andrew Jones top!, with 1700 runs at 54.9.... then Javed, Mark Taylor, Robin Smith, Border, Richards)
Just 4x players were averaging 45-50,
and another 7 players were averaging over 40 (so 17 in total), and 20th was Greg Matthews averaging 39.19.
At end of 1981
4x 50+ averages (Richards top with 60, then Javed, Chappell G, Gavaskar)
Just 3 players averaging between 45-50 and another 7 40-45.
20th best was Vengsarkar, averaging 36.7 at the time.
Of course there were just 6 test sides vs the 10 that have contributed players to lists in later years...
At end of 1971,
Just 2 players averaging over 50 (Sobers and Walters)
only 5 more averaging 45+, and just 5 more 40+
the 20th best average was Asif Iqbal on 33.3
At end of 1961
5x 50+ : Sobers, Barrington, O'Neill, Saeed Ahmed, Worrell
4x 45-50, and 8 more over 40, and 20th was Graveney at 39.2
At end of 1951 there were 8x players averaging over 50 - Worrell, Weekes, Harvey, Hutton, Hazare, Nourse, Morris, Compton
I haven't checked all the lower-average players here, and I suspect there might not actually be 20 players with 1000 runs given how few tests most non Aus or Eng players would have played at this point.
All numbers calculated fairly manually so there may be errors, and there could be arguments over who was a current player at any point in time. Eg if a player played their last test in 1970 but were still playing first class cricket in 1971, should they be in the 1971 list? I've excluded them... Likewise someone like Bert Sutcliffe who seemingly retired in 1959 but played 8 tests in 1965, is not included in the 1961 numbers... But I did include players if there was just a 1-2 year gap in an otherwise consistent career. Eg, Chris Gayle is in 2011's numbers even though he didn't play a test in that year, given he played 12 tests in the next three years.