Hello,
I did some calculations on the elongations (angular distances from Sun) of the planets using Solar Fire. The period that I ran the calculations is 1 Jan 1900 to 31 Dec 2100 (200 years).

Mercury
Maximum elongation whether Direct or Retrograde = 27d47m24s.
Maximum elongation when Direct = 27d47m24s
Maximum elongation when Retrograde = 21d44m24s
Maximum elongation from among the Stationary Retrogrades = 21d22m48s
Minimum elongation from among the Stationary Retrogrades = 13d31m12s
Maximum elongation from among the Stationary Directs = 21d44m24s
Minimum elongation from among the Stationary Directs = 13d33m0s
Maximum number of days in retrograde motion = 25
Minimum number of days in retrograde motion = 19
Percentage of time (not space!) spent on Retrograde Motion = 23.57%

Venus
Maximum elongation whether Direct or Retrograde = 47d16m12s.
Maximum elongation when Direct = 47d16m12s
Maximum elongation when Retrograde = 29d02m24s
Maximum elongation from among the Stationary Retrogrades = 29d02m24s
Minimum elongation from among the Stationary Retrogrades = 27d19m48s
Maximum elongation from among the Stationary Directs = 28d54m0s
Minimum elongation from among the Stationary Directs = 27d15m0s
Maximum number of days in retrograde motion = 43
Minimum number of days in retrograde motion = 40
Percentage of time(not space!) spent on Retrograde Motion = 7.71%

Mars
Maximum elongation from among the Stationary Retrogrades = 147d05m24s
Minimum elongation from among the Stationary Retrogrades = 129d36m36s
Maximum elongation from among the Stationary Directs = 146d58m12s
Minimum elongation from among the Stationary Directs = 129d33m0s
Maximum number of days in retrograde motion = 81
Minimum number of days in retrograde motion = 59
Percentage of time (not space!) spent on Retrograde Motion = 10.37%

Jupiter
Maximum elongation from among the Stationary Retrogrades = 119d39m0s
Minimum elongation from among the Stationary Retrogrades = 115d39m0s
Maximum elongation from among the Stationary Directs = 119d34m12s
Minimum elongation from among the Stationary Directs = 115d37m48s
Maximum number of days in retrograde motion = 121
Minimum number of days in retrograde motion = 114
Percentage of time (not space!) spent on Retrograde Motion = 41.75%%

Saturn
Maximum elongation from among the Stationary Retrogrades = 112d53m24s
Minimum elongation from among the Stationary Retrogrades = 111d32m24s
Maximum elongation from among the Stationary Directs = 112d49m12s
Minimum elongation from among the Stationary Directs = 111d29m24s
Maximum number of days in retrograde motion = 136
Minimum number of days in retrograde motion = 128
Percentage of time (not space!) spent on Retrograde Motion = 53.5%%