Frequency adverbs are adverbs that state how often something happens or someone does something. The most common frequency adverbs in English are [roughly]:
Always – about100% of the time
Frequently - about 90% of the time
Usually - about 80% of the time
Often - about 70% of the time
Sometimes - about 50% of the time
Occasionally - about 40% of the time
Seldom - about 20% of the time
Rarely - about 10% of the time
Never - about 00% of the time
Find below links to the eslgold.com site on 'frequency adverbs' quoted in the Powerpoint; two sets of 'frequency adverb' exercises each from englisch-hilfen.de and the British Councils' learnenglish.org.uk site; and, a Frequency Adverbs Multiple Choice from esl.lbcc.ca.us
Links:
1. Frequency Adverbs [eslgold.com]
2. Position of Adverbs of Frequency Exercies [englisch-hilfen.de] 1 2
3. Frequency Adverbs Game [learnenglish.org.uk] 1 2
4. Frequency Adverbs Multiple Choice [esl.lbcc.cc.ca.us]