adverb
BAD : We see each other mostly every day.
GOOD : We see each other almost every day.
BAD : Mostly every family has a television.
GOOD : Nearly every family has a television.
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Use almost/nearly with all/every/everyone etc (NOT mostly ): 'Almost everyone in the office has had a cold recently.'
Compare: 'The students here are mostly Swiss or German.' (= most of the students here ... )