I want to keep the same meaning, but help me improving it in terms of writing style
We are proud of ourselves for having successfully brought smiles on the face of one family every day in last four decades.
So I can write it as:
We are proud that we have brought smiles to one family for every day in the past 40 years
We are proud that we have brought smiles to one family every day in the past 40 years
we are so proud of having brought smiles to one family for the past 40 years.
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