SingularPlural
I have been walkingwe have been walking
you have been walkingyou have been walking
he/she/it has been walkingthey have been walking

SingularPlural
I have been sleepingwe have been sleeping
you have been sleepingyou have been sleeping
he/she/it has been sleepingthey have been sleeping

SingularPlural
There is no present perfect progressive for the "to be" verb. "Have been being" is expressed simply as "have been": "We have been being successful in the past."