After three straight months of declining confidence, Americans’ optimism toward the economy grew slightly last month, according to the RBC CASH (Consumer Attitudes and Spending by Household) Index. The index for May stands at 87.1, just above April’s 85.4 level. The survey, conducted early last week, found that respondents’ were more positive about current economic conditions, although less optimistic about their future prospects. RBC said the survey reflected fears over rising gas prices, a sagging housing market and a concern about the job market outlook.