A risk manager is evaluating the price sensitivity of an investment-grade callable bond. The manager gathers the following information on the bond as well as on the embedded option:

Interest rate level	Callable bond	Call option
3.95%	97.9430	2.1972
4.00%	97.8910	2.1090
4.05%	97.8566	2.0035

Assuming the current interest rate curve is flat at 4%, what is the estimated effective convexity of the callable bond?