Musical composition can be viewed as an act of conditional problem solving, the realization of musical ideas by arranging notes spatially and temporally. The resulting creations may constitute the unique style of the composer. In this paper we focus on how chord voicing -- the expression of chords by choosing and stacking musical notes -- has evolved in western classial piano music using large-scale music data sets. Our results shows that the level and variety of voicing novelty have increased throughout history. We also find that some composers exhibit a high level of voicing novelty due to the utilization of innovative pitch class sets, while others actually have pushed the boundaries of voicing with traditional pitch class sets. This study helps us to probe the emergence of expression of musical style on note level and to understand the evolutionary pattern of note arrangements.