Why is that only Pakistan always produce great all round bowling units....?

It's quite obvious that Pakistan is he only team that always have good all round bowling attack And every other country seems to produce great bowlers either fast bowlers or spinners.

if you look at Australia they always produce fast bowlers, bowlers who try to ball real fast and they haven't produced great swing bowlers McGrath was an exception there. And exept for Warne they haven't produced a effective spin bowler.

England, always have good swing bowlers, not really quick bowlers. And same as Australia they haven't produced a good spinner except for Swann. (Of course Panesar is an indian)

South Africa, well I even can't remember their spinners name except for Paul Adams cuz of his strange bowling action.

Ind and SL are all about spinners. even though Vaas and Zaheer were great swing bowlers.

NZ and WI, fast bowlers.

but,

Pakistan

Fast bowlers(very sharp) - Akhthar, Sami, Mohommad Irfan...etc

Swing bowlers - Akram, Younis, Junaid Khan, Asif, Tanveer..etc

Spinners - ajmal, Mushtaq Ahmed , Saqlain Mushtaq...etc.

Pakistan too have same conditions asSri Lanka and India. So what could be the reason...?