Long-term fluxes or integral fluences of solar energetic particle (SEP) and their variability within and beyond the 11-year solar cycle makes an important information for Space Physics. However, large uncertainties exist in evaluation of the average SEP fluxes or fluences over the last decades as assessed by different methods and from different datasets. Here we re-visit the derivation of annual integral SEP fluences from available data based on in-situ measurements since 1984. We have reconstructed a full time series of integral SEP fluxes above 10, 30, 60, 100 and 200MeV for the period from 1984 to 2019 using observations performed by the GOES satellites. Intercalibration of the fluxes was performed via a linear relation between overlapping pairs of observations in order to obtain a uniform dataset. Galactic cosmic ray (GCR) background subtraction and identification of SEP event periods was carefully performed, allowing for precise calculation of annual SEP fluences. Annual integral fluences of SEPs with energies above 10, 30, 60, 100 and 200MeV have been calculated for the period from 1984 to 2019 (solar cycles 22-24) along with uncertainties. It is shown that solar cycle 24 was significantly (factor of 5-8) weaker in the SEP fluence than the preceding cycles 22 and 23. The cumulative occurrence probability of years with the fluence above a given value is found to be perfectly described by the Weibull distribution. This can be used as a projection for the occurrence of solar extreme eruptive events on the secular time scales. In addition to the annual fluences, a dataset containing hourly integral SEP fluxes is available at the CDS.