When did the fifty-overs format for One-day international matches comes in practice?

Question

In the early days of ODI cricket, the number of overs was generally 60 overs per side, and matches were also played with 40, 45 or 55 overs per side, but now it has been uniformly fixed at 50 overs.
- Wikipedia

• What are all the over formats used in ODI history?
• When did the 50-overs format for one-day international matches comes in practice?

Answer if possible,

• How many matches were played for only 50-overs till now?

FYI, 5th ODI between Australia and England is the 3416th ODI match in Cricket history.

Answer 1

What are all the over formats used in ODI history?

As already mentioned 40, 45, 55, 60, 50 and 35 overs.

When did the 50-overs format for one-day international matches comes in practice?

I didn't find any source or article where it is mentioned. But I find it by reading scoreboards of ODI matches one by one from starting. The first 50 overs ODI was West Indies v Pakistan, ODI no. 41, played at Albion Sports Complex, Albion, Guyana in 16 March 1977.

Note that earlier in ODI format, the number of overs was not fixed. You can see scoreboard of each ODI match by year here.

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Update:

Looking at this post it is clear that the ODI format of 50 overs per side came in practice from 1979/80 in Australia with colored cloths and day\night match. From that season most teams started following 50-overs format except England which continued playing 55-overs ODI at home until 1995. However, England also started playing 50-overs match at home from 1996 v India. From that 50-overs format remained in ODI.