Since the discovery of superconductivity, the record transition temperature held by a material has been shattered many times. Here is an excellent plot (taken from here) that shows the critical temperature vs. year of discovery:
This is a pretty remarkable plot for many reasons. One is the dramatic increase in transition temperature ushered in by the cuprates after approximately 70 years of steady and slow increases in transition temperatures. Another more worrying signature of the plot is that we are currently going through an unprecedented drought (not caused by climate change). The highest transition temperature has not been raised (at ambient pressures) for more than 23 years, the longest in history since the discovery of superconductivity.
It was always going to be difficult to increase the transition temperatures of superconductors once the materials in the cuprate class were (seemingly) exhausted. It is interesting to see, however, that the mode of discovery has altered markedly compared with years prior. Nowadays, vertical lines are more common, with a subsequent leveling out. Hopefully the vertical line will reach room temperature sooner rather than later. I, personally, hope to still be around when room temperature superconductivity is achieved — it will be an interesting time to be alive.