Adverbs of Frequency

100%	always
	usually
	frequently
	often
50%	sometimes
	occasionally
	rarely
	seldom
	hardly ever
0%	nev

Adverbs of Frequency answer the question "How often?" or "How frequently?" They tell us how often somebody does something.

Adverbs of frequency come before the main verb (except the main verb "to be"):

• We usually go shopping on Saturday.
• I have often done that.
• She is always late.

Occasionally, sometimes, often, frequently and usually can also go at the beginning or end of a sentence:

• Sometimes they come and stay with us.
• I play tennis occasionally.

Rarely and seldom can also go at the end of a sentence (often with "very"):

• We see them rarely.
• John eats meat very seldom.

Check your understanding here.

Source: englishclub.com