SC-190 visa is taking time in 2018

Hi, from the dashboards, we can see that the SC-190 visa were granted in 60-90 days in 2016/2017 mostly if it was direct grant or first CO contact within 90 days for 80% of applicants. But in 2018, why SC 190 visa taking time around 90-100 days for either direct grant or CO contact… Particularly it was noticed that in between April end to May mid for Victoria, its very slow. Can anyone shed ur views and know the reasons ?