Step 1: Understanding the Concept:
Select the most idiomatic expression for describing a steady, continuous increase over time.
Step 2: Key Formula or Approach:
Approach: While "annually" is correct, "year by year" is a standard idiomatic phrase emphasizing progression.
Step 3: Detailed Explanation:
The sentence aims to show the consistent growth of a large resource (talent).
"Year by year" suggests a gradual but constant accumulation, which fits the admiring tone of the sentence better than the drier "annually."
Step 4: Final Answer:
The most suitable alternative is "year by year."