We prove an explicit improvement to the known lower bound on the proportion of nontrivial zeros of the Riemann zeta function lying on the critical line Re(s) = 1/2. The key ingredient is the combination of two existing results. Platt–Trudgian (2021) proved that every nontrivial zero ρ of ζ(s) with 0 < Im(ρ) ≤ T_v = 3×10¹² lies on the critical line, giving a verified count of N(T_v) = 1.236×10¹³ zeros. Bui–Conrey–Young (2011) proved that at least 41.05% of all zeros up to height T lie on the critical line, for all sufficiently large T. Combining these by a two-part decomposition yields: for all T ≥ T_v, N₀(T)/N(T) ≥ 0.4105 + 0.5895 · N(T_v)/N(T) This bound improves on the Bui–Conrey–Young record for all finite T, approaching 41.05% asymptotically as T → ∞. At T = 10¹³ the bound gives 57.95%; at T = 4.34×10¹³ it gives more than 50%. As a corollary, for all T ≤ 4.34×10¹³, a strict majority of the nontrivial zeros of ζ(s) lie on the critical line. The proof requires no new analytic machinery. It is a direct consequence of combining verified computational data with the best known asymptotic mollifier result. This paper constitutes Strategy A in a two-part programme toward an asymptotic improvement; Strategy B — improving the Levinson mollifier itself using the Platt zeros to reduce error terms — is the subject of forthcoming work.