The frequency of occurrence of racially charged terms such as "ching chong" might be a reflection of societal attitudes toward Chinese. One quick, but very rough, gauge of anti-Chinese sentiment might be historical trends in the occurrence of such terms in books.
Google's Ngram viewer provides such data, but it does not examine the context of the occurrence, only raw frequencies. Nor does it examine newspapers or other media. So,with that warning, here is a chart for occurrences of "ching-chong." The derisive phrase has shown a consistent pattern rising slowly from the 1930s to mid 1960s and then rising sharply to the present.
For comparison, "Chinaman's chance" is included. It was not an epithet but rather a metaphor for a variety of 'lost causes' or hopeless situations such as that which Chinese suffered from racism. Its peak frequency was in the 1930s, perhaps due to the Great Depression, dropped in the 1950s, a period of prosperity. It peaked again in the 70s and then has declined and leveled off as of 2000.
In summary, 'ching chong,' a mocking taunt, has increased over the last 70+ years. How well it can serve as a barometer of anti-Chinese feeling is ambiguous and it needs to be compared with other indicators. In contrast, the metaphorical 'Chinaman's Chance' has fluctuated perhaps with the hopeful or hopelessness of the era.
Note: These terms were used prior to 1900, but their relative frequencies were too low to show up on the graph in comparison to the more recent years. In contrast, two other terms, Chinee and Chinaman, were not graphed because their relative frequencies were far greater than ching chong and Chinaman's chance.
At the bottom of an actual Ngram chart (not on this jpeg image), if you click on the years, you can see excerpts from books showing the actual context of the term.
One other note: the high frequency of "Chinee" was largely due to the popularity of Bret Harte's classic 1870 "Heathen Chinee" poem and to a lesser extent, "Jolly Chinee" fairy tale children's stories by E. Veale (1896).