Such swings are far larger than the typical year-to-year fluctuations, the superintendents said.

Dr. White said many factors may contribute to year-to-year fluctuations in the number of cases.

Exxon has tried to build a very large presence systematically, without paying much attention to month-to-month or even year-to-year fluctuations in oil prices.

However, despite some year-to-year fluctuations, the percentage of students dropping out of school each year has stayed relatively the same since 1987.

The economic riskiness of life has increased: year-to-year fluctuations in family income have grown much larger.

That fund's investors are more likely to aim for long-term gains and to worry less about year-to-year fluctuations because of aggressive management.

Since 1979, Antarctica's sea ice has increased slightly, but year-to-year fluctuations are large.

Meanwhile, economic security is a thing of the past: year-to-year fluctuations in the incomes of working families are far larger than they were a generation ago.

He said the administration would work with Congress to smooth year-to-year fluctuations in highway spending.

You also find oxygen-18 values to differ among different summers or different winters, because of unpredictable year-to-year fluctuations in temperature.