Solaris Date format help please

I have list of dates in a file. Am reading each line and trying to format date, Can you please help me ?

Sample file content:

02/22/16 USA is great country
02/21/16 USA future
02/23/16 who is he

I want to read each line from above file and format date as below

2016-02-21

(i.e., using the date utility format +%Y-%m-%d )

Can you please help me? Appreciate your help

1. What have you tried to do this on your own?
2. Are you trying to do this with a shell script?
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3. If not, what programming language do you want to use?
4. If so, what shell are you using?
5. Do you have the GNU utilities installed on your Solaris system?
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6. Is the date always the 1st "word" on a line in your file?
7. Does every line in your file contain a date to be modified?
8. Are all of your dates in the 21st century?