My rough guess (for f2p) would be in the 80k range for a year. Would need near perfect daily activity though. There maybe something I'm not factoring in.

This is what I came up with for a yearly total for a fairly dedicated f2p. If I have made any mistakes, please point them out for me. I'm sure there well be a few :P

Daily

Convoy and Plunder: 130 (assuming not getting plundered)

Wishing tree: 20 (avg. of lvl. 9-10 tree)

1 hour online: 10

Group wheel: 10 (low ball avg.)

170 per day. (62050 per year)

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Weekly

Summon capture: 160

Client log in: 100 (New)

Weekend mission: 20 (rough avg.)

280 per week. (14560 per year)

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Monthly

Sign in: 250 (3000 per year)

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Seasonal

Final reward: 500 per season. Top 15 ranking each season (2000 total)

Medals: 420 per season, avg. player. (1680 total)

Monthly boxes: 60 per month (720 total)

(4400 per year)

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62050 + 14560 + 3000 + 4400 = 84010 coupons per year.

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Not included: Survival trial,,Cat quiz, Plot instance chapter completion, Mt. Myoboku trial,

Wishing lanterns, Home mission board, Level gift packs, Season tickets. (sure I'm missing others)