Also Ehsan bhai remember, Imran (88 tests) has most 10-wicket match hauls (6) in tests among all Pakistani bowlers. He achieved that in his 71st test in the Caribbean in 1988. 3 of his 6 hauls were in away series - Sydney 1977, Headingley (Leeds) 1987 and Bourda (Caribbean) 1988
Both Waqar (87 tests) & Wasim (104 tests) took 10 wickets 5 times each, though Waqar played 17 tests fewer than Wasim.
I followed the careers of Imran, Wasim and Waqar very closely. By the end of the three-test series in the Caribbean in 1988, Imran had 334 wickets in 73 tests at a bowling average of 20. Wasim never achieved such a high average at any stage in his career. And Waqar's bowling average was an astonishing 18 or 19 in his first 35 tests or so. So he exploded from the outset whereas both Imran and Wasim were late bloomers. And Waqar was never the same bowler again after 1996 once his pace dropped following a stress fracture of back.
In his last 15 tests, Imran played in the side mainly as a captain and batsman - remember he averaged 50+ with the bat in 48 tests as captain as well - bowling just a few overs in each test. By then he was in his late 30s, his pace had declined and Imran's bowling stats suffered if anything. So to still end hs career with a bowling average of 22.81 is great credit to Imran Khan.